This invention relates to a multiple voltage motor control and in particular to a single releasable connector unit for selectively energizing a motor for either of two operating voltages.
Alternating current motors are widely used as power drives for operating other mechanisms. Alternating current motors are specially constructed to operate at different voltages in accordance with the power supply voltages available in the conventional power distribution systems and the like. Conventionally, single phase motors will be operated at 115 volts or 230 volts, while three phase motors will be operating at 230 or 460 volts, depending upon the particular application, the availability of such voltages, and the like. Any given motor by proper design can be constructed as a dual voltage motor which can be operated at either one of the two basic power supplies by providing proper circuit connection between the power supply and the several motor windings. Additionally, single phase motors can reverse the direction of rotation by reversing of the winding connection to the power supply. More particularly, AC motor windings are conventionally formed with multiple coils. The individual coils are connected in different circuit configurations to accommodate the different voltages. The end terminals for the coils and the power supply terminals may of course be terminated in an accessible part of the motor. The user can then properly interconnect the several coils to each other and to the incoming power supply lines for a particular voltage and/or rotation. The individual connection is of course not only time consuming, but the result is highly dependent upon the skill and attention of the service person making the appropriate connection. In order to avoid the costly time associated with personnel-dependent connection of the motor windings, as well as the effect of human error, various switching and plug-in type connector units have been developed to permit simple user selection of the appropriate winding connections. In such system, a pin and socket connector unit may be provided. The motor mounted part includes internal connection of the coil ends and the power supply lines to a multiple socket unit. A selection plug is then provided with a similar array of connected prongs or pins for insertion into the socket unit which creates a connection of the winding ends to each other and to the line terminals for appropriate voltage selection. For example, U.S. Pat. No. 3,602,748 discloses a typical plug-in unit for voltage selection. The coil ends or terminations are connected to a terminal unit mounted within the motor. The terminal unit includes an individual terminal pin units for each coil end or interconnected ends. A shorting socket unit is provided having mating complementing terminal sockets. The socket unit can be inserted in alternate orientations, each of which is related to a particular voltage. Connectors of the socket and shorting plug type may also be constructed and arranged to provide reversal of the rotational output of the motor. The motor winding connections internally and to the power supply lines may not only determine the voltage but the direction of rotation of the rotor, and therefore the motor output. Thus, generally by reversing of the power supply lines connection in a single phase motor, the direction of rotation of the motor can be reversed. U.S. Pat. No. 4,211,962 which issued July 8, 1980, for example discloses a special D.C. brushless reversibly motor having a connector unit of a socket and jack type connected respectively to the motor and to a supply and commutating circuit. The contacts of the respective socket and jack are similarly arrayed such that 180.degree. rotation of the plug results in reversing rotational direction of the motor.
U.S. Pat. No. 3,602,748 which issued Aug. 31, 1971, discloses another typical plug-in connector for a three-phase dual-voltage motor. The jack or cap member is shown coupled to the power supply lined and the plug is connected to the motor windings. A separate cap member is provided for each voltage and includes appropriate internal jumper leads for connecting of the proper winding terminals to each other and to the desired voltage.
U.S. Pat. No. 2,922,054 which issued Jan. 19, 1960, discloses a motor having a socket unit mounted to the motor as an integrated assembly with a shorting plug adapted to be inserted into the socket unit to control the winding connection. Thus, appropriate labels may be provided. Alernatively, multiple socket elements may be provided to receive a voltage socket, such as shown in applicant's patent application Ser. No. 06/428,997 which was filed on Sept. 30, 1982 entitled "Multiple Voltage Motor Connection Apparatus" by the inventor Wesley Anderson now abandoned. In the above entitled application, a separate socket unit is provided for each voltage. A single plug-in unit is provided for selective insertion into the two sockets for selection of the two different voltages.
Other similar plug-in type units are shown for example in the following issued patents. Generally, all such patents disclose plug-in type units particularly the tailor design tailored to a particular motor construction.
Typically, in the prior art voltage selection systems, each type of motor is provided with a separate and uniquely related and custom designed voltage selection system. Thus, a socket and plug-in unit is specially constructed for each given motor design. Other motors have individual custom designed plug-in connector units. However, complete separate design for various motors adds to the cost of the individual motors. Although the given cost increase for any given motor may be economically justified, there is of course a continuing demand in the field, particularly for high production motors, to minimize such costs and thereby contribute to the more economic and efficient production of motors.
The plug-in connector must of course permit convenient packaging in or to the motor, while providing readily understood and accessible manipulation of the motor connection for field installation of the power supply and selection of the proper motor connection for the incoming power supply. The various motors may or may not require use of a thermal overload protector. Where used, the protector is conventionally mounted within the motor and hardwired directly to the winding circuit. This is not accomplished in the field if the protection is in the motor. External overloads may be applied, however, in the supply system.
The inventor's analysis of the prior commercial art has indicated the need and demand from the purchasers for a simplified but reliable and economic multiple contact releasable connector which can be universally applied to a line of multiple voltage motors including both single phase motors and polyphase motors.